The easiest way to do this properly for most household items is
1. get a signed receipt (usually blank) from Goodwill. I assume that
you already have this.
2. Make an itemized list of the donated items - doesn't have to be
too itemized, just "5 men's pants, 2 women's blouses" will be fine.
3. Go to your favorite search engine like Yahoo or Google and search for
"Goodwill Valuation Guide". You will get a number of hits. Pick a
Goodwill website (i.e., "goodwill" is in the link name) nearest your
location (usually a state or region) and work your way down to the Valuation
Guide. These guides show the typical low and high prices that Goodwill
sells household items for in their thrift stores. I typically take the low
price and the high price and average them, and use the result as my valuation
for each type of item.
Take the value for each type of article and multiply it time the number of
articles of each type, and then add it all up. There's what you report on
Schedule A for non-cash contributions.
NOTE: if the value of your deduction is over $500, then you will need
to file a form 8283. If your item is more than $5000, then you will
probably need a formal appraisal. Please read the instructions for Line
17 in the IRS
Instructions for Schedule A.
